# Full text of "The Flow Of Gases In Furnaces"

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```DESIGN OF OPEN-HEARTH FURNACES

197

large jets of air and gas from the ports must be given time to mix.
With too short a furnace the flame will extend beyond the hearth.
With too long a furnace the gases of combustion will tend to drop
below the bath temperature.

There are three limitations on the width of the furnace:

1.  The distance material can be thrown through the door by
expert manipulation of a shovel or a dolomite gun.

2.  The width the flame can be spread.

3.  The limitation due to the strength of the roof.

The first controls patching and making bottom. Furnaces
have been built to 16.75 ft wide. This is rather close to the limit.

Table 2 gives the hearth dimensions of a number of furnaces
in service. It shows a considerable diversity in the ideas regarding
this portion of the furnace. Table 3 gives the minimum and
maximum values from Table 2.

TABLE 1

HEARTH AREA OP OPEN-HEARTH FURNACES FOR VARIOUS DEPTHS OF MOLTEN

METAL

Depth of Bath of Molten Metal, In.

Capacity
Cu Ft of

i

of Furnace,
TV\T1C!
Molten Metal
12
15
18
21
24
27
30
33
36

JL ons

(Hearth area in square feet)

15
78.45
235
188
157
135
118

20
104 . 60
314
252
212
180
157
139

25
130.75
392
314
262
225
196
174

30
156.90
471
376
314
270
235
209
189

35
183.05
549
440
356
316
275
244
220
201

40
209 . 20
628
504
420
360
314
278
256
229
209

50
261 . 50
785
629
525
450
392
350
325
286
262

60
313.80
941
755
629
542
471
418
377
343
314

75
392.25
1177
940
785
674
588
523
470
429
392

90
470.70
1412
1130
945
812
706
628
567
515
471

100
523.00
1569
1255
1050
900
785
697
629
573
523

Allow from 3 to 6 in for cinder and boil.

y

Formula:   3— ~A.    In which
d

volume of molten metal in charge;

d = depth of bath ; metal only ; A = area of hearth required.   Weight of molten
metal, 430 Ib per cubic foot; 5.23 cu ft per ton.```